<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>边框案例</title>
	<style>
		/
		
		div{
			width: 400px ;
			height: 400px;
			border: 1px solid red   ;
			border-radius: 50%;
			
			
			
			
			
			/*2222*/
			div#triangle{
				width: 0;
				border:-left:50px solid transparent;
				border-right: 50px solid transparent;
			    border-bottom: 50px solid black;
			}
			
			
			
			
			
	
			
		}
		
		
		
	</style>
	</head>
	
	<body>
		
	<div id="cirle"></div>	
	<div id="triangle"></div>	
	
		
		
		
	</body>
</html>